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This article will explain in detail how to achieve multi-process programming in PHP. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

Creation of child processes

A general subprocess is written as follows:

In the above code, if the child process is created successfully, the system will have two processes, one for the parent and one for the child, and the id number of the child process is $pid. When the system runs to $pid = pcntl_fork ();, branch at this place, and the parent and child processes each start running their own program code. The result of the code is parent and child. Isn't it strange that a code with mutual exclusion of if and else outputs the result? In fact, as mentioned above, when the code is in pcntl_fork, a parent process runs parent and a child process runs child. Parent and child are shown in the code results. As for the question of who comes first, it depends on the allocation of system resources.

If you need to start multiple processes to process data, you can start a sub-process according to the amount of data, such as 1000 processes. Just use the for loop.

# if the total number obtained is less than or equal to 0, wait 60 seconds and exit if ($count 1000) {$cycleSize = ceil ($count/1000);} else {$cycleSize = 1;} for ($iTun0; $I 0) {$myId = pcntl_waitpid (- 1, $status, WNOHANG); foreach ($pidArr as $key = > $pid) {if ($myId = $pid) unset ($pidArr [$key]);}

Then use crontab to make the PHP program execute automatically at regular intervals.

Of course, the sample code is relatively simple, and you need to consider how to prevent multiple child processes from executing to the same data or when the current process has not finished processing data, crontab starts to execute PHP files to enable new processes, and so on.

PHP multi-process implementation

Let's systematically sort out the implementation of PHP multi-processes:

1. Direct mode

Pcntl_fork () creates a process. The return value in the parent process is the pid of the child process, and the return value in the child process indicates that the creation process failed. It's very similar to C.

Test script test.php

Run from the command line

# php-f test.php

Output result

Parent start, pid 17931793 2013-01-14 15:04:17parent continue1793 2013-01-14 15:04:18child start, pid 17941794 2013-01-14 15 15:04:18child start 04 15:04:18child start 181794 2013-01-14 15 15:04:17parent continue1793 04lane 191793 2013-01-14 15 pid 04lane 191794 2013-01-14 15 15:04:20parent continue1793 2013-01-14 15:04:20child start Pid 17951795 2013-01-14 15 15:04:22parent continue1793 04Rd 2017931794 2013-01-14 15 15:04:22child start 2017931794 2013-01-14 15 15:04:22child start Pid 17961796 2013-01-14 1515-01-14 15V 04R 231796 2013-01-14 15V 04R 231795 2013-01-14 15V 04R 231795 2013-01-14 1514 04Rover 241796 2013-01-14 1504Rd 241796 2013-01-14 1504Rd 241796 2013-01-14 154Rd 04Rich 251796 2013-01-14 15:04:26

You can see that three child processes are created and run in parallel with the parent process. One of the lines has a different format from the others.

17931794 2013-01-14 15 purl 04purl 212013-01-14 15:04:21

There is a conflict because the two processes write at the same time.

two。 Blocking mode

In a direct way, after the parent process creates the child process, it does not wait for the child process to finish, but continues to run. There doesn't seem to be any problem here. If the php script does not end automatically after running, but resides in memory, it will cause the problem that the child process cannot be recycled. The zombie process. You can wait for the end of the process through the pcntl_wai () method, and then recycle the finished process.

Change the test script to:

$pid = pcntl_fork (); if ($pid = =-1) {...} else if ($pid > 0) {echo "parent continue\ n"; pcntl_wait ($status); for ($kryp0; $k)

Run from the command line

# php-f test.php &

Output result

Parent start, pid 20662066 2013-01-14 16:45:34parent continue2066 2013-01-14 16:45:35child start, pid 20672067 2013-01-14 16 16:45:35child start 45 16:45:35child start 3520662067 2013-01-14 16 parent start 362013-01-14 16 16:45:37parent continue2066 362067 2013-01-14 2013-01-14 16:45:37child start Pid 20682068 2013-01-14 16 16:45:41signel 4540 402068 2013-01-14 1614 1616:45:40child start 382066 2013-01-14 16:45:38parent continue2066 2013-01-14 1614 16:45:40child start, pid 20692069 2067 2013-01-14 161414402068 2013-01-14 161414402068 2013-01-14 1614Rod 452066 2013-01-14 16Ranger 45402066 2013-01-14 16Ranger 45402066 2013-01-14 16Ranger 412069 2013-01-14 1615 16:45:41signel 17 received child end pid 2067 Status 02069 2013-01-14 16 received child end pid 45 received child end pid 422068 2013-01-14 16 received child end pid 45 422069 2013-01-14 16:45:43signel 17 received child end pid 2068, status 02069 2013-01-14 16:45:44signel 17 received child end pid 2069, status 0

Multiple processes are running in parallel again, and after about 10 seconds of running, use ps-ef | grep php to view the running process, there is only one process

Lqling 2066 1388 0 16:45 pts/1 00:00:00 php-f t5.php

It is the parent process, and the child process is recycled.

Child process exit status

Pcntl_waitpid (- 1, $status, WNOHANG) $status

Returns the end state of the child process

Multithreading under windows

Windows system does not support the pcntl function, fortunately there is curl_multi_exec () this tool, the use of internal multithreading, access to multiple links, each link can be used as a task.

Scripting test1.php

Scripting test2.php

Run from the command line

# php-f test1.php &

Output result

Task 0 [http://localhost/feedbowl/t2.php?job=task1] get:child start, pid 58045804 2013-01-15 20 task 22 20:22:39task 355804 2013-01-15 20 get:child start 2013-01-15 20 22 http://localhost/feedbowl/t2.php?job=task1] 356 804 2013-01-15 20 22 http://localhost/feedbowl/t2.php?job=task1] 375804 2013-01-15 20 task 2013-01-15 20 pid 2238 5804 2013-01-15 20:22:39task 1 [2013-01-15] Pid 58045804 2013-01-15 20 20:22:39task 22 20:22:39task 58045804 355 804 2013-01-15 20 20 20:22:39task 22 get:child start, pid 58045 804 2013-01-15 20 20 20:22:39task 22 20:22:39task 2 [2013-01-15 20 20 20:22:39task 2 [2013 get:child start, pid 58045804 2013-01-15 20 20:22:39task 2 [2013 get:child start, pid 58045804 2013-01-15 20 20:22:39task 22 20:22:39task 2 [2013-01-15 20]

From the time of printing, multiple tasks are running almost at the same time.

This is the end of this article on "how to achieve multi-process programming in PHP". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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